An Efficient Homemade Wood Furnace

For poor [workshop from scratch], winter brings the joy of a cold workshop. Since the building is structurally made from tin, warming up the room is difficult.

Naturally, the solution was to construct a homemade wood furnace. The build starts off with an angle grinder being taken to a compressed air tank. After sawing off the top and sanding down the edges, the builder slices out an opening and welds together some rods into a stand for the center. He then proceeds to weld some external frames for the furnace, as well as a chimney stack, some nifty covers joined by hinges, and a fan/temperature regulator to keep the fire going.

Most of the pieces seem to come from scrap metal lying around the workshop, although the degree to which the entire project comes together is quite smooth. Some filter and spray paint do the trick for cleaning up the furnace and making it look less scrappy. The last step? A stack of wooden logs and a blow torch to start the fun. Outside of the furnace, an LCD screen keeps track of the temperature, giving some feedback and control.

The result is perhaps a too effective at warming up the workshop, but the problem sure is solved!

Continue reading “An Efficient Homemade Wood Furnace”

Turning Scrap Metal Into Something To Work With

Blacksmiths will frequently work to a customer’s commission, and sometimes those commissions can be somewhat unusual. [Copperrein] had just such a piece of work come his way, a ceremonial sword to be made from a supplied collection of iron and steel items. To render them into something useful he had to melt them together, and the story of how he did that is particularly interesting.

We’re introduced to the Aristotle furnace, a fairly simple top-fed air blast charcoal furnace capable of melting almost any ferrous scrap into a so-called “bloom”, a lump of iron with some slag and carbon inclusions. These furnaces are often built as holes in the ground, but he’s made his atop a portable forge at working height to save bending over it for seven hours.

The source material was a very mixed bag, so the first order was to strip it in an acid bath of any coatings which might contaminate the resulting bloom. The parts, including things as diverse as a huge wrought-iton bolt, a scythe blade, and a pair of dividers, were then cut into small pieces one by one and fed into the furnace. They melt as they progress down through the furnace, resulting in a bloom of iron. The bloom is impure and will need significant working to expel any inclusions, but the final result will be something like the wrought iron of old. Let’s hope he has a power hammer, working the bloom would be hard work by hand!

If this catches your attention, you may be interested in a bit of blast furnace iron smelting. And of course, there is also our ongoing blacksmithing series to get you going at the anvil. You could even make a nail.

Via Reddit.

Thanks [Mike] for the tip.

How To Build A Small Metal Furnace At Home

Casting is a great way to make your own custom metal parts. However, casting requires some manner of furnace capable of generating high enough temperatures to melt the metal in question. Few of us have these just lying around, but never fear. It’s possible to build a basic gas-powered furnace at home, with commonly available materials (Youtube link, embedded below).

This furnace is the work of [Ahmed Ghr], and is as simple a build as they come. The idea is to produce a mold in which to cast concrete to create the furnace. A steel bucket is cut up and used as the outside of the mold, with a pipe inserted in the base to act as a feeder for air and gas. A plastic bucket is then inserted within the steel bucket and held in place with spacers, to create the inner combustion cavity. Concrete is poured in and allowed to set. Once finished, the steel bucket is cut away, and a fire is built over the furnace to melt away the plastic inside. Similar techniques are used to produce the lid, and the furnace is completed.

It’s a build that is executed with the most basic of tools, and should serve as a capable furnace for lower melting point metals at the very least. We’ve seen a lot of cement projects lately, as it turns out. Video after the break.

Continue reading “How To Build A Small Metal Furnace At Home”

DIY Tube Oven Brings The Heat To Homebrew Semiconductor Fab

Specialized processes require specialized tools and instruments, and processes don’t get much more specialized than the making of semiconductors. There’s a huge industry devoted to making the equipment needed for semiconductor fabrication plants, but most of it is fabulously expensive and out of reach to the home gamer. Besides, where’s the fun in buying when you can build your own fab lab stuff, like this DIY tube oven?

A tube oven isn’t much more complicated than it sounds — it’s just a tube that gets hot. Really, really hot — [Nixie] is shooting for 1,200 °C. Not just any materials will do for such an oven, of course, and this one is built out of blocks of fused alumina ceramic. The cavity for the tube was machined with a hole saw and a homebrew jig that keeps everything aligned; at first we wondered why he didn’t use his lathe, but then we realized that chucking a brittle block of ceramic would probably not end well. A smaller hole saw was used to make trenches for the Kanthal heating element and the whole thing was put in a custom stainless enclosure. A second post covers the control electronics and test runs up to 1,000°C, which ends up looking a little like the Eye of Sauron.

We’ve been following [Nixie]’s home semiconductor fab buildout for a while now, starting with a sputtering rig for thin-film deposition. It’s been interesting to watch the progress, and we’re eager to see where this all leads.

Fail Of The Week: When Good Foundries Go Bad

Like many of us, [Tony] was entranced by the idea of casting metal, and set about building the tools he’d need to melt aluminum for lost-PLA casting. Little did he know that he was about to exceed the limits of his system and melt a hole in his patio.

[Tony]’s tale of woe begins innocently enough, and where it usually begins for wannabe metal casters: with [The King of Random]’s homemade foundry-in-a-bucket. It’s just a steel pail with a homebrew refractory lining poured in place, with a hole near the bottom to act as a nozzle for forced air, or tuyère. [Tony]’s build followed the plans pretty faithfully, but lacking the spent fire extinguisher [The King] used for a crucible in the original build, he improvised and used the bottom of an old propane cylinder. A test firing with barbecue charcoal sort of worked, but it was clear that more heat was needed. So [Tony] got hold of some fine Welsh anthracite coal, which is where the fun began. With the extra heat, the foundry became a mini-blast furnace that melted the thin steel crucible, dumping the molten aluminum into the raging coal fire. The video below shows the near catastrophe, and we hope that once [Tony] changed his pants, he hustled off to buy a cheap graphite or ceramic crucible for the next firing.

All kidding aside, this is a vivid reminder of the stakes when something unexpected (or entirely predictable) goes wrong, and the need to be prepared to deal with it. A bucket of dry sand to smother a fire might be a good idea, and protective clothing is a must. And it pays to manage your work area to minimize potential collateral damage, too — we doubt that patio will ever be the same again.

Continue reading “Fail Of The Week: When Good Foundries Go Bad”

Move Over Aluminum: Cast Iron For The Home Foundry

When it comes to choice of metals that can be melted in the home foundry, it’s a little like [Henry Ford]’s famous quip: you can melt any metal you want, as long as it’s aluminum. Not that there’s anything wrong with that; there’s a lot you can accomplish by casting aluminum. But imagine what you could accomplish by recycling cast iron instead.

It looks like [luckygen1001] knows a thing or two about slinging hot metal around. The video below shows a fairly expansive shop and some pretty unique tools he uses to recycle cast iron; we were especially impressed with the rig he uses to handle the glowing crucibles from a respectful distance. The cast iron comes from a cheap and abundant source: car disc brake rotors. Usually available free for the asking at the local brake shop, he scores them with an angle grinder and busts them into manageable chunks with a hammer before committing them to the flames. The furnace itself is quite a thing, running on a mixture of diesel and waste motor oil and sounding for all the world like a jet engine starting up. [luckygen1001] had to play with the melt, adding lumps of ferrosilicon alloy to get a cast iron with better machining properties than the original rotors. It’s an interesting lesson in metallurgy, as well as a graphic example of how not to make a flask for molding cast iron.

Cast iron from the home shop opens up a lot of possibilities. A homemade cast aluminum lathe is one thing, but one with cast iron parts would be even better. And if you use a lot of brake rotors for your homebrew cast iron lathe, it might require special handling.

Continue reading “Move Over Aluminum: Cast Iron For The Home Foundry”

Cook Up Your Own High-Temperature Superconductors

It looks more like a charcoal briquette than anything, but the black brittle thing at the bottom of [Ben Krasnow]’s crucible is actually a superconducting ceramic that can levitate magnets when it’s sitting in liquid nitrogen. And with [Ben]’s help, you can make some too.

Superconductors that can work at the relatively high temperature of liquid nitrogen instead of ultracold liquid helium are pretty easy to come by commercially, so if you’re looking to just float a few magnets, it would be a lot easier to just hit eBay. But getting there is half the fun, and from the look of the energetic reaction in the video below, [Ben] had some fun with this. The superconductor in question here is a mix of yttrium, barium, and copper oxide that goes by the merciful acronym YBCO.

The easy way to make YBCO involves multiple rounds of pulverizing yttrium oxide, barium chloride carbonate, and copper oxide together and heating them in a furnace. That works, sort of, but [Ben] wanted more, so he performed a pyrophoric reaction instead. By boiling down an aqueous solution of the three components, a thick sludge results that eventually self-ignites in a spectacular way. The YBCO residue is cooked in a kiln with oxygen blowing over it, and the resulting puck has all the magical properties of superconductors. There’s a lot of detail in the video, and the experiments [Ben] does with his YBCO are pretty fascinating too.

Things are always interesting in [Ben Krasnow]’s life, and there seem to be few areas he’s not interested in. Of course we’ve seen his DIY CAT scanner, his ruby laser, and recently, his homemade photochromic glass.

Continue reading “Cook Up Your Own High-Temperature Superconductors”